Microsoft Word C043580e doc Reference number ISO/TR 15658 2009(E) © ISO 2009 TECHNICAL REPORT ISO/TR 15658 First edition 2009 08 01 Fire resistance tests — Guidelines for the design and conduct of non[.]
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© ISO 2009
TECHNICAL REPORT
ISO/TR 15658
First edition2009-08-01
Fire resistance tests — Guidelines for the design and conduct of non-furnace-based large-scale tests and simulation
Essais de résistance au feu — Lignes directrices pour la conception et
la conduite d'essais et de simulations à large échelle non basés sur les fours
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Foreword iv
Introduction v
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Test design requirements 2
4.1 General 2
4.2 Ambient environmental conditions 2
4.3 Size of the test assembly 3
4.4 Construction of the test assembly 4
4.5 Test specimen 5
4.6 Selection of heating conditions 6
4.7 Selection of ventilation conditions 7
4.8 Selection of exhaust conditions 7
4.9 Selection of decay conditions (if controlled) 8
5 Test conditions 8
5.1 Ambient conditions 8
5.2 Test conditions — Thermal 9
5.3 Test conditions — Pressure 9
5.4 Test conditions — Mechanical 10
5.5 Timing of the test 10
5.6 Output measurements 10
5.7 Data recording and storage 11
6 Test procedure 11
6.1 Ignition 11
6.2 Safety procedures 11
6.3 Monitoring 11
6.4 Observations 12
6.5 Termination and extinguishing 12
6.6 Post-test analysis 12
7 Test report 12
7.1 Stating the objective 12
7.2 Characterization of the experimental conditions 12
7.3 Expression of the results 12
7.4 Description of the test specimen 13
7.5 Reporting — Electronic media 13
7.6 Expression of the validity or field of application of the result 13
Bibliography 14
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International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2
The main task of technical committees is to prepare International Standards Draft International Standards adopted by the technical committees are circulated to the member bodies for voting Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote
In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights ISO shall not be held responsible for identifying any or all such patent rights
ISO/TR 15658 was prepared by Technical Committee ISO/TC 92, Fire Safety, Subcommittee SC 2, Fire
Containment
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b) interaction between components or elements;
c) fire loads and heating rates;
d) achievement of realistic levels of restraint;
e) realistic oxygen availability
Fire modelling is also being increasingly used to resolve the complex problems that many modern buildings produce Currently, modelling is often limited by a lack of data and large-scale “natural” tests are increasingly being used to establish the missing information, and, by using the protocol described in this Technical Report, the quality, comparability and validity of the information/data should be significantly improved
Unfortunately, the design of such tests is often controlled by the availability of space, equipment, cost, environment, etc and these sometimes compromise the scientific value of the experiment and make the results hard to compare with other experiments performed in other laboratories or countries This lack of comparability has in the past prevented the value of the findings from being maximized
When an experiment has been set-up without adequate consideration of the objectives and the test parameters, it is difficult to apply a scientifically valid field of application to the result As a consequence, the data of findings are frequently wrongly applied to constructions subsequent to the test
The objective of this Technical Report is to harmonize the approach to the design, performance and reporting
of such experiments, in order to increase the possibility of comparing information and also to develop meaningful fields of application of the results It is not the objective of this Technical Report to inhibit the development of ad-hoc or natural tests, but more to encourage their development, while at the same time increasing their scientific value
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Fire resistance tests — Guidelines for the design and conduct
of non-furnace-based large-scale tests and simulation
CAUTION — The attention of all persons concerned with managing and carrying out this fire resistance test is drawn to the fact that fire testing may be hazardous and that there is a possibility that toxic and/or harmful smoke and gases can be evolved during the test Mechanical and operational hazards may also arise during the construction of the test elements of structures, their testing and disposal of test residues
An assessment of all potential hazards and risks to health shall be made and safety precautions shall
be identified and provided Written safety instructions shall be issued Appropriate training shall be given to relevant personnel Laboratory personnel shall ensure that they follow written safety instructions at all times
1 Scope
This Technical Report specifies procedures for the design, performance and reporting of fire tests which are not performed using standardized test equipment, such as furnaces or test chambers, and which are primarily duration- or time-based
It is applicable to all “natural” fire tests, which set out to evaluate the behaviour of structural frames, rooms (or
a suite of rooms forming part of a building), with respect to fully developed fire conditions, regardless of whether or not the heat input is by means of natural sources, e.g cribs or burners It is not applicable to
“reaction-to-fire” large-scale tests, which are primarily designed to evaluate materials and for which the heating rate is slower and the maximum rate of heat release is lower than that which would occur at full development
In the context of this Technical Report “large” means tests in which the flame has a width of 1 m or more This Technical Report is intended for use by the designers of fire tests (laboratories, regulatory authorities and researchers) and for those responsible for disseminating the information and applying the results in practice
The following referenced documents are indispensable for the application of this document For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies
ISO 13943, Fire safety — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943 apply
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4.1 General
The difficulties experienced when testing “large” structures, e.g space, cost, instrumentation and material handling equipment, often cause a desire to scale down the construction being tested In fire testing, this is difficult because the response of the members forming part of a construction varies considerably as a result of their mass The thermal inertia of an element is a major influence on its thermal response Similarly, when direct heating is used in an experiment, such as an item or items of furniture, timber cribs, or even gas burners, the size of the flame and the convective plume cannot meaningfully be scaled down commensurate with any proposed reduction in volume of the test chamber or the elements forming it Reducing the size of the test assembly is often not an option when performing such tests Where the experiment has to be scaled down in size and where it can be demonstrated that the influence on the thermal response of the structure can be quantified, the largest influence that a reduction in size has is in respect of the time at which critical events happen When reducing the size of an enclosure the behaviour is modelled more accurately if the heat losses can be made to reflect the actual conditions relative to the volume/area of the space Any such change shall
be quantified and recorded
Before commencing the design or construction of a test assembly, it is important for the designers to identify the objectives of the experiment as, in many cases, they define the scale and size of the construction being evaluated The objectives shall form part of the test report
When designing and setting up an experiment involving a large-scale fire test, there are a number of test parameters capable of influencing the results of the test significantly Many of these influences can be avoided
if sufficient thought is given to the parameter when planning an experiment If unavoidable, the influence can
be anticipated and hence compensated for when performing the test and analysing the results Guidance on the possible influence of these factors is given in 4.2 to 4.9
The outcome of the analysis and the selection of the parameters used shall form part of the test characterization and shall be reported as proposed in 7.2
4.2 Ambient environmental conditions
4.2.1 Air currents, magnitude and direction
Air movement around the construction, which either contains the fire or is the subject of the analysis, can seriously influence the experiment and the results obtained Air flow directly onto ventilation apertures can produce a pressure within the cell or room which can influence the rate at which gases may egress through gaps or apertures, possibly having a scouring effect Air flow across or away from such a ventilation opening can create a vacuum on that face drawing gases out and possibly affecting the rate of burning due to a shortage in the supply of oxygen
Whilst still air produces the most neutral conditions, it is not easy to provide this for large-scale experiments due to the lack of buildings able to house fire tests of this size Equally, still air conditions are not representative of the in-use conditions, where winds or draughts exist 90% of the time
The ambient air movement conditions used in the test should be justified, whether still or moving, and if moving, the velocity and direction shall form part of that analysis
4.2.2 Temperature
Ambient temperature affects the time at which any temperature-sensitive material reaches its critical temperature, whether that is an ignition temperature or a phase change If the ambient temperatures are unusually low, these temperatures are reached after an unrealistically long time, whereas if they are high, they can be reached unexpectedly early The greater the mass of the temperature-sensitive material, the slower is the thermal response In an anticipated chain reaction, i.e spread of fire from one object to another, the influence of temperature is compounded, each phase being influenced independently
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The ambient temperature, not only at the beginning of the test, but for a period prior to the test, which is related to the thermal inertia of the materials, shall be justified and related to the anticipated in-use conditions Where in practice a wide range of temperatures can be expected, for instance from −5 °C to +40 °C, it can be necessary to perform separate tests at each end of the anticipated scale, if the influence cannot be readily modelled If it can, a mean temperature should be used
4.2.3 Humidity
The humidity of the air affects the moisture content of low-mass hygroscopic materials, which may influence their propensity to ignite and burn, if they form part of the construction being evaluated Similarly, high moisture content and humidity can directly affect the characteristics of heat transfer and it is important to take the prevailing conditions into account when analysing the results
When timber (or other forms of cellulosic material) is being used as the fuel source, the moisture content affects the rate of heat release Guidance on this subject can be found in the Loss Prevention Council Report
TE 91338-40[6] All fuel timber should be controlled to the required moisture content right up until the time of the test
4.3 Size of the test assembly
4.3.1 Justification for shape
The shape (numbers of sides forming the enclosures) of a test room influences the response of the structure
to fire If the product is to be used in rectangular spaces only, this is probably the correct way of testing If other applications exist, i.e for cylindrical or spherical constructions, the application of the result produced in a rectangular test arrangement should be considered and justified when it is used in areas with a differently shaped boundary It is common in any heating experiment for boundary layers to become established on surfaces, particularly in the corners of rooms or where there is a change in geometry which influences the heat exchange on these surfaces This influence should be analysed and allowed for when applying the findings to structures with other shapes, e.g curvilinear
4.3.2 Justification for height
The height of a test chamber probably has a greater influence on the fire dynamics and response of the structure than any other parameter Because fire spread is initially a vertical phenomenon, the inclusion of any ceiling, roof or horizontal closure (lid) causes the fire to spread laterally Combustion gases rising as a result
of convective air currents cool due to the dilution with air, which becomes entrained into the plume and also transfer heat to the environment as the height increases As a consequence, the position of a horizontal membrane determines the temperature of the gases when they start to spread laterally This can influence the temperature and depth of boundary layers, which can significantly change the feedback to other items of fuel
in the space
It is important that the height of the ceiling/roof/horizontal membrane be considered in the light of the influence
it can have on the development of the fire conditions The height used shall be related to the in-use conditions,
in respect of the fire load as well as its size and position The height from the top of the heat source to the ceiling is important in fire growth models as it influences the plume behaviour and the radiative feedback from the gas layer The height of the ceiling above the floor is important if flame impingement is anticipated in practice
4.3.3 Justification for width and depth
While the height of the test assembly is the primary influence on the response of the structure with respect to convection (see 4.3.2), the width and depth of the chamber influence the response of the structure to radiation The proximity of the walls to the heat source can produce dramatically different findings if they are receiving
an unrealistically high flux relative to the hazard being reproduced Because of the rate at which radiation intensity decays with distance, the horizontal distances between the heat source and heated surfaces is not
as critical as the height, because there is no convective component in the heat trawler horizontally Where the relationship between ignition/fire source and the perimeter of the chamber is known to have an influence, the test assembly should be related to the scenario being evaluated
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4.4 Construction of the test assembly
4.4.1 Physical characteristics of elements not forming part of the test specimen
The test assembly can consist of an assembly of the elements which are the subject of the test or can consist
of a number of fixed elements forming part of a test rig to which are attached the element or elements which are being evaluated These fixed elements provide the methods of supporting the test specimens or providing fixity and/or restraint As such their physical characteristics are important, especially at the test temperature The critical physical characteristics of the testing that shall be justified are:
a) the material type, thickness and density of the fixed elements;
b) hot strength/load-bearing capacity;
c) the effectiveness of the fixings available for the attachment of the test specimens;
d) the quality and nature of the seal which can be provided between the rig and the specimen
4.4.2 Thermal characteristics of elements not forming part of the test specimen
The thermal characteristics of elements only used to close off the test construction can play an important role
in creating the exposure conditions of the specimen Where the specimen conditions of use are known, e.g a composite floor on top of an otherwise stone or concrete room structure, non-specimen elements used in the test assembly should replicate these If they do not replicate the in-use construction, any variation shall be justified The justification should consider the following parameters:
a) combustibility;
b) thermal diffusivity, α, where α = k/ρc with k is thermal conductivity, ρ is density and c is specific heat
Thermal diffusity, α, provides a means to measure a material's ability to conduct thermal energy relative
to its ability to store thermal energy Materials with a larger thermal diffusity, α, should respond to thermal changes more quickly than materials with a smaller thermal diffusivity, α;
c) coefficient of expansion;
d) propensity to bow (due to temperature differentials)
Where the in-use conditions are not known, any test report should fully characterize these parameters to aid subsequent analysis
4.4.3 Attaching the specimen to the test construction
The method of fixing any single element to the adjacent structure can influence its thermal response If the end use is known, the method of attachment should reflect that as far as is practical When the end use in practice is not known, the fixing method should be fully characterized, describing:
a) the type of fixing;
b) the materials from which the fixings are made;
c) the frequency of fixings;
d) any measured torque forces, if fixings are screwed;
e) any critical temperatures related to the effectiveness of the fixing material, if non-mechanical fixings are used
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In the case of load-bearing assemblies, the levels of fixing and restraint should be quantified and where possible related to the actual levels of restraint expected
4.4.4 Sealing of the specimen into the test structure
The sealing of the specimen into the test structure is normally only critical if the test assembly is being evaluated for its ability to contain fire spread However, if an edge member is to be evaluated for load-bearing capacity, the seal may influence just how much of that member is heated When the seal does not represent the in-use condition, the material and method chosen shall be justified and the seal should be fully characterized with respect to the following characteristics:
a) the dimensions, particularly the depth in the case of a linear gap seal;
b) the composition/nature of the material;
c) its physical state, e.g rigid, flexible or compressible;
d) any known thermal characteristics, e.g softening temperature, activation temperature and expansion ratio (in the case of heat-activated materials)
4.5.1 Construction of the test specimen
It is assumed that most of the test specimen is manufactured/constructed as it would be when in use, as this
is presumably the subject of the test However, for purposes of practicality, it may be necessary to introduce additional or non-representative joints When introducing such joints the influence of the joint on the following parameters shall be considered:
a) heat transfer between elements and through the element;
b) the integrity of the specimen;
c) the thermal expansion and distortion of the specimen;
d) the transfer of load, both applied and thermally induced
When the jointing incorporates seals, these should be characterized as proposed in 4.4.4
4.5.2 Materials for the test specimen
The selection of the materials used for the test specimen shall replicate those in the element to be used However, when constructing specimens for the test it shall be recognized that some of the materials are out of balance with those used in practice as a result of the time they have to age or condition Time should be allowed for them to achieve equilibrium with the environment and unless impossible, also to achieve the same state of cure as in practice If it is impractical to achieve either, the difference between the tested condition and the actual condition should be determined Non-homogeneous materials should be made in as similar a manner as possible to those being duplicated The factors that shall be justified are:
a) the moisture content (for hygroscopic materials);
b) the curing for hydraulic-based materials;
c) the chemical reaction for compounds;
d) the strength of any bonding materials/adhesives